The present invention relates generally to verification of computer storage devices. In particular, the invention relates to a method and apparatus for verifying memories with a high level of security and confidence.
For many applications, it is necessary to verify the contents of computer storage devices to confirm that no corruption of data has occurred. Verification is especially important in areas where individuals may seek to alter the contents of a computer memory such as banking, state lottery applications, and other gaming operations, including slot and video gaming machines. To date, a program or set of data stored in a computer memory has been verified for authenticity by carrying out a number of steps. First, the memory chip is removed from the circuit board in which it is integrated. Second, the contents of each memory address is compared to a master chip containing a known data set. Third, if the contents of the tested chip match those of the master chip, the chip is replaced in the circuit board from which it was removed. However, if the contents do not match, the chip is replaced with a new one, the contents of which do match those of the master chip.
The problem with the previously known technique for verifying the contents of computer storage devices is that each chip must be individually removed and verified. In many cases, the devices to be checked are located in a wide range of geographic locations. This means that the party charged with verification must be physically present at the site of the device to be tested and remove each and every individual chip for testing. In the case of a lottery where hundreds, or even thousands of machines may be spread across one or more states, verification becomes impractical. Knowledge of the effort required to verify each individual machine may entice less scrupulous individuals to alter the memory of such a device in an attempt to set the outcome or otherwise cheat the lottery terminal. Of course, the same principals apply to bank machines, slot machines, or any other machine where an altering of the memory would benefit the person making the alteration.
Another problem associated with physical verification at the site of the device relates to the ability to download data from a central computer to devices connected in a network. Downloading allows a program or data to be sent from one device to another without the two devices being physically proximate to one another. However, if it is necessary to verify that the integrity of the downloaded data has been maintained, the convenience of downloading may be defeated because it would still be necessary to perform verification at the site of the machine to which the program or data is downloaded. Due to the problems presented, it is desirable to achieve an invention capable of remote verification of computer storage devices.